FULL PRODUCT VERSION :
Java(TM) SE Runtime Environment (build1.6.0-internal-fastdebug-tonyd_21_jul_2008_15_00-b00)

ADDITIONAL OS VERSION INFORMATION :
Os independent (will happen on any OS).

A DESCRIPTION OF THE PROBLEM :
There is a memory leak in j2se/src/share/classes/sun/font/StrikeCache.java which can occur when disposeStrike is called for a FontStrikeDisposer that has no glyph images. In this case, the memory allocated for the pScalerContext is never freed.

The fix is to add a final else if clause to free the scaler context at line 217.

e.g.:

static void disposeStrike(FontStrikeDisposer disposer) {
        if (disposer.intGlyphImages != null) {
            freeIntMemory(disposer.intGlyphImages,
                          disposer.pScalerContext);
        } else if (disposer.longGlyphImages != null) {
            freeLongMemory(disposer.longGlyphImages,
                           disposer.pScalerContext);
        } else if (disposer.segIntGlyphImages != null) {
            /* NB Now making multiple JNI calls in this case.
             * But assuming that there's a reasonable amount of locality
             * rather than sparse references then it should be OK.
             */
            for (int i=0; i<disposer.segIntGlyphImages.length; i++) {
                if (disposer.segIntGlyphImages[i] != null) {
                    freeIntMemory(disposer.segIntGlyphImages[i],
                                  disposer.pScalerContext);
                    /* native will only free the scaler context once */
                    disposer.pScalerContext = 0L;
                    disposer.segIntGlyphImages[i] = null;
                }
            }
            /* This may appear inefficient but it should only be invoked
             * for a strike that never was asked to rasterise a glyph.
             */
            if (disposer.pScalerContext != 0L) {
                freeIntMemory(new int[0], disposer.pScalerContext);
            }
        } else if (disposer.segLongGlyphImages != null) {
            for (int i=0; i<disposer.segLongGlyphImages.length; i++) {
                if (disposer.segLongGlyphImages[i] != null) {
                    freeLongMemory(disposer.segLongGlyphImages[i],
                                   disposer.pScalerContext);
                    disposer.pScalerContext = 0L;
                    disposer.segLongGlyphImages[i] = null;
                }
            }
            if (disposer.pScalerContext != 0L) {
                freeLongMemory(new long[0], disposer.pScalerContext);
            }
        }
// NEW ELSE IF CLAUSE HERE!
        else if (disposer.pScalerContext != 0L) {
            // tpd - If we never had glyph images, but we did allocate
            //       a scaler context, we must free the scaler context!
            freeIntMemory(new int[0], disposer.pScalerContext);
        }


It would be great if this fix could be integrated into an upcoming release!

Thanks,
  Tony



REPRODUCIBILITY :
This bug can be reproduced always.
Posted Date : 2008-07-23 10:56:50.0

N/A

Suggested fix is partly correct. Needs distinguish the 32 bit and 64 bit cases :

        } else if (disposer.pScalerContext != 0L) {
            /* Rarely a strike may have been created that never cached
             * any glyphs. In this case we still want to free the scaler
             * context.
             */
            if (FontManager.longAddresses) {
                freeLongMemory(new long[0], disposer.pScalerContext); 
            } else {
                freeIntMemory(new int[0], disposer.pScalerContext);
            }
        }
Posted Date : 2008-07-23 17:51:05.0